Digital compact disks were originally conceived in the early 1980's as a technique to accurately copy and preserve audio recordings intended for sale to a mass market of consumers. As computing power has increased exponentially since that time, information processing tasks unthinkable only a few years ago have become commonplace and require large amounts of data most economically and conveniently stored on digital compact disks.
Until recently the transfer of data onto compact digital disks was a costly procedure economically feasible only when manufacturing a large quantity of copies. Users whose applications required relatively few copies or required frequent data updates could not reap the benefits of this technology, even though low-cost disk-readers were readily available.
The advent of recordable digital compact disks, generally referred to as "CD-R" disks, was intended to allow users to record their own disks and thereby achieve significant savings. Unlike a common compact disk that has been pressed by a mold, a CD-R has a dye layer that is etched by a laser contained in the CD-R disk drive. Once etched, the "burned" CD-R disk is unalterable and will retain data for approximately 75 years.
Despite their overall durability, compact disks are still prone to damage caused by improper handling. A compact disk is especially susceptible to surface scratches large enough to defeat the disk's internal error correction coding. Disks that are subject to large amounts of the physical handling, either manually by humans or automatically by computer systems, are most vulnerable.
Compact disk users now avoid this problem through use of disk caddies that protect the compact disk while allowing an input or output device access to the surface of the disk. The standard caddy somewhat resembles a 3.25 inch floppy disk case enlarged to the size of a audio compact disk "jewel box". Similar to a floppy disk case, the caddy has a spring-loaded metallic sleeve that protects a section of the open face of the compact disk. Once inserted into a caddy-compatible disk read/write unit, the metallic sleeve is pushed away and input/output operations may be performed on the compact disk.
Conventional CD-R copiers generally lack the ability to handle recordable disks that have been pre-loaded into caddies. In this situation, users must manually remove all caddies before loading the CD-R copier and then reinstall all caddies after completion of copying, increasing the likelihood of damage to the compact disks created by careless handling.
Added to this expense in a volume copying process is the necessity for direct human supervision to prepare CD-R disks for copying, remove the disks from the CD-R disk writer once copying is complete, and then prepare the disks for inspection to ensure no defective disks are retained in the completed set of copies. Aside from the tedium involved that may indirectly add errors, requiring human attention in this process adds a significant labor cost that is added to the end-user price.
Finally, conventional CD-R copiers may include additional hardware necessary to protect compact disks from damage during transport through the CD-R copier. A CD-R copier that accepts caddies can make use of simpler, more efficient design and still produce perfect copies.
This system copies a stack of caddy-loaded recordable disks and eliminates the necessity of direct human supervision of the copy process, through an efficient caddy transport mechanism that minimizes moving parts and is inexpensive to manufacture. Another benefit provided by the open design of the caddy transport mechanism is that in the unlikely event the caddy transport mechanism becomes inoperable, users may easily troubleshoot and fix the mechanism.
Yet another benefit provided by this system is the system's ability to test burned disks for disk write errors, and through use of a separator ramp, discharge a caddy containing a defective disk into a defect bin, thus isolating the defective disks from the set of properly burned disks.
Yet another benefit provided by this system is the system's ability to automatically transfer data located on disks in several caddies to a host computer connected to the copy unit. This process is easily accomplished by loading the caddies containing the source data into the gravity-fed hopper and programming the system to read the source data off of the compact disks held by the caddies and then transfer the source data to the hard-disk drive of the host computer connected to the copy unit.